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Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Funded by the EU’sLIFE programme
Field Identification GuidePhytophthora ramorum
Phytophthora ramorum is an aggressive fungus-like pathogen that causes extensive damage to a wide range of trees and shrubs. The disease affects the foliage and bark of a number of both broadleaved and conifer trees and is particularly prevalent on the western side of the UK where climatic conditions favour its growth and spread. When multiple hosts occur on infected sites, symptoms of P. ramorum are likely to occur in a variety of species. The disease is often fatal to the trees it affects and it has had a major impact on forestry in the UK.
Species affected Phytophthora ramorum can infect numerous tree and shrub hosts, which can be divided into two host types:
(1) ‘Sporulating/spore-producing’ or ‘foliar’ hosts whose leaves are susceptible to the disease. The pathogen is able to reproduce in, and spread from, these hosts to produce new infections on the same or different hosts.
(2) ‘Terminal’ hosts are those within which the pathogen cannot easily reproduce or from which it cannot spread. Development of symptoms in terminal hosts may take a number of years before the infection becomes severe enough to be fatal. In these hosts the bark rather than the leaves is susceptible to infection.
The main sporulating forestry hosts in the UK are larch (Larix spp.), rhododendron (Rhododendron ponticum), Vaccinium myrtillus and sweet chestnut (Castanea sativa). In larch, both the leaves and the bark are susceptible to the disease. In areas of high inoculation, the foliage of native oak species has also been infected.
Terminal hosts include broadleaved trees such as European beech (Fagus sylvatica), southern beech (Nothofagus spp.), oaks (Quercus spp.) including the northern red oak (Q. rubra), Turkey oak (Q. cerris), holm oak (Q. ilex), horse chestnut (Aesculus hippocastanum) and birch (Betula spp.). The disease can also affect a number of conifers including grand fir (Abies grandis), noble fir (Abies procera), Douglas fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla). It has also occasionally been found on Sitka spruce (Picea sitchensis). In most cases, bark infections are a result of infection by spores that have spread from the leaves/needles of nearby sporulating hosts such as rhododendron or larch.
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Phytophthora ramorum
Signs and symptoms
The signs and symptoms of this disease vary according to the host species it is affecting.
On larch:An obvious symptom of P. ramorum disease is the occurrence of bleeding cankers on the bark of side shoots, branches and the main stem of infected trees. Profuse production of a sticky, translucent resin is often associated with these cankers and this becomes white and crusty with age. As lesions underlying the bleeding cankers girdle shoots, branches and stems, the tree’s needles become a distinctive yellow/ginger colour. The girdling lesions also cause partial or complete dieback of branches and the crowns of infected trees. Partial or abnormal needle flushing and retention of dead/dying needles is also a common symptom on infected trees. Epicormic growth (profuse sprouting) may be visible among dead branches and the crowns of infected trees. Larch trees can be killed rapidly (within 2–3 years of infection), especially after suffering multiple aerial infections on branches and stems.
Foliar symptoms which are specifically associated with sporulation of the pathogen include wilted, withered shoot tips with blackened needles often with a dark grey/purple hue. The infected shoots can shed their needles prematurely with just the needles at the shoot tips remaining. Flushing of buds can also be abnormal or completely aborted.
Look-alike symptoms such as shoot dieback and discoloured, distorted needles can be caused by larch woolly aphids (adelgids/sap-sucking insects). The needles can become a purplish brown colour before they drop. However, secretions of a white waxy wool can distinguish infestations of adelgids from symptoms of P. ramorum on larch needles. In heavy infestations the tree can begin to die back with the needles becoming a yellow colour. Infestations of other insects such as the larch case-bearer (Coleophora laricella) may also result in discoloured and dead needles in larch. Another pest that causes look-alike symptoms in larch is the bark boring beetle Ips cembrae, which introduces a pathogenic fungus to its host tree as it bores into the main stem for breeding. The disease lesions and galleries caused by the beetle larvae in combination eventually become extensive and girdle the tree,
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resulting in the tops of the trees becoming discoloured and dying. The presence of the galleries in the bark distinguishes a P. ramorum infection from an infestation by I. cembrae. Top death in larch is also a feature of drought stress to which larch is particularly vulnerable.
Needle cast diseases and needle blights can also affect larch species, with the main symptoms being discoloration and dieback of needles and defoliation of shoots. The fungal pathogen Meria laricis causes one such disease in which the needles at the tip of the shoots look green and healthy while the needles along the length of the shoot have died. Sirococcus conigenus is another fungus that can cause shoot blight in larch. Bark-killing fungi such as Cytospora spp. and Allantophomopsis pseudotsugae (previously known as Phacidium coniferarum) cause shoot death when the lesions they produce girdle the base of the shoot, thereby depriving the tree of water. Cankers on the bark of larch can also be caused by the fungus Lachnellula willkommii.
Discoloration and death of foliage in the crowns of larch trees can also be caused by squirrel damage to the bark of branches and stems.
On Rhododendron ponticum: Typical foliar symptoms include leaf-blackening, wilted leaves and shoots and shoot dieback. The leaf stalks of infected leaves can become blackened, with the discoloration extending into the leaf along the midrib. Blackening at the leaf tip can also occur and this will again progress along the midrib towards the leaf base and stalk. Watery lesions with undefined margins develop in leaves as the infection advances within the leaf tissue. The infection process can occur rapidly, causing the shoots to wilt and the leaves to hang down. Shoot dieback originating at the shoot tip and extending downwards, causing shoots to have a bent over/shepherd's crook appearance, is also a common symptom of P. ramorum in rhododendron. Lesions or cankers may form on twigs or stems, progressing back from, or spreading into, side shoots and leaves. Cankers near ground level can cause rapid wilting of shoots and leaves.
Other Phytophthora species and honey fungus (Armillaria spp.) can also affect roots of rhododendron causing
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symptoms such as wilting, yellow or sparse foliage and shoot and branch dieback. Other pathogens can cause blotches on the leaves of rhododendron, for example the fungal leaf spot fungus (Glomerella cingulata), but they do not follow the same disease pattern as P. ramorum and are often circular in appearance and also often have a purple halo around the circumference of the lesion. P. kernoviae is another fungal pathogen that causes similar symptoms to those of P. ramorum on rhododendron.
On Vaccinium myrtillus:Vaccinium myrtillus is susceptible to P. ramorum and infection among plants spreads through open heath and causes extensive dieback. Symptoms include leaf necrosis, blackened shoots and dieback. P. kernoviae also infects V. myrtillus and produces symptoms that are almost identical to those of P. ramorum. V. myrtillus is also susceptible to other Phytophthoras. V. myrtillus will exhibit dieback if its roots are affected by pathogens or abiotic factors. V. myrtillus is also susceptible to a fungal rust disease caused by Calyptospora goeppertiana, which causes deformation and browning of shoots ('witches' brooms') and a reduction in leaf size.
On sweet chestnut: Foliar symptoms include wilting, and leaves with ‘water-soaked’ or discoloured margins. The petioles of infected leaves may also be blackened, with the discoloration extending along the midrib of the leaf. Infected leaves can be shed prematurely and may be present beneath affected trees. Other symptoms of P. ramorum infection on sweet chestnut include profuse epicormic growth at the base of the stem, often with retained symptomatic foliage. Infected trees can also display a progressive year-on-year decline. Lesions can develop on the bark of infected sweet chestnut trees.
Other Phytophthora species such as P. cinnamomi and P. cambivora can infect and kill roots of sweet chestnut trees and cause cankers on the base of infected trees leading to dieback in the crown. Pathogenic fungi such as Cryphonectria parasitica (causes chestnut blight; a priority pathogen which is notifiable) and Gnomoniopsis smithogylvii can also cause cankers on the bark of sweet chestnut trees leading to
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dieback in the shoots and branches.
On the bark of other broadleaved trees such as beech: The symptoms on broadleaved trees such as beech, oak and southern beech are mainly bark lesions which exude fluid from infected areas. The exudate is often a dark colour which can dry to a crust on the outer bark of the tree. The inner bark underneath bleeding areas is discoloured (usually brown) and dying. There may be many, or just a few, lesions on a single tree with the size of the lesions varying. The lesions are usually found on the lower stem, but are occasionally up to a few metres above ground level.
P. ramorum lesions do not extend below the soil line and do not appear to infect root systems. When the lesions become extensive on, or girdle, the main stem, the tree will die. Bleeding lesions on the stems and branches of broadleaved trees can result from infection by honey fungus (Armillaria spp.) and other Phytophthora species such as P. pseudosyringae and P. kernoviae. Bleeds on oak trees may also result from acute oak decline (an Observatree priority disease). However, acute oak decline bleeds tend to be a very dark brown and originate from between cracks in bark plates at heights of 1 metre plus, whereas Phytophthora bleeds on oak tend to be more black/purple and originate randomly from areas of the lower stem.
Timing On larch:Yellowing or gingering of needles will often be the first visible sign of infection and can be observed when the larch is bearing needles from May to October. The foliar symptoms associated with the pathogen sporulating (e.g. wilting shoot tips, purple/black needles and premature needle drop) are most likely to be seen at the beginning of the autumn, in September and October. During the winter, retained needles indicating sudden death of branches or some or all of the crown, may be visible. Lesions/bleeding cankers on the stems and branches can be present all year round but may be easier to see in the winter when the foliage is absent.
On Rhododendron ponticum:Leaf lesions, wilt and shoot and twig cankers may be visible all year round.
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Based on information available in December 2017.
On Vaccinium myrtillus:Symptoms can be seen all year round.
On sweet chestnut:Symptoms on the leaves can be observed throughout summer until the leaves fall in the autumn. Bark cankers may be visible all year round.
On the bark of other broadleaved trees such as beech:Lesions and bleeds can be observed on branches and stems all year round but may be easier to see in the winter when leaves are absent.
Biosecurity P. ramorum spreads through soil, organic matter, mists and rainsplash. Transportation and movement of infected plants is also a key means of long-distance spread. Precautions such as cleaning and disinfecting footwear and tools before and after a site visit are essential and can be a legal requirement in outbreak areas to prevent further spread. Remember to check clothing such as collars, inside boots, hoods and outer pockets too. Keep vehicles on hard tracks and ensure that they are kept clean so that they are easier to disinfect when necessary and check them over for any plant material before leaving an infected site. In larch, rhododendron and V. myrtillus infected areas, tree needles/leaves and soil are the main risks, especially if they are wet. Surface water such as puddles also increases the risk of spread. Even after felling and removal of infected larch trees, infective spores may still persist on needles and in the soil.
Reporting requirements
This is a notifiable pathogen so if you find it you must report it. Please report through Tree Alert (www.forestry.gov.uk/treealert).
In Northern Ireland please report via the TreeCheck website (www.treecheck.net) or phone app, or by [email protected]
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Impact of Phytophthora ramorum on larch at a landscape scale. The healthy trees are bright green in colour and the infected trees are a grey-brown colour.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Healthy trees
Infected trees
Signs and symptoms on larch
9
Japanese larch trees (Larix kaempferi) infected with Phytophthora ramorum.
Phot
ogra
ph: C
live
Bras
ier,
Fore
stry
Com
mis
sion
Signs and symptoms on larch
10
Dieback of Japanese larch (L. kaempferi) caused by Phytophthora ramorum. Individual branches or complete crowns can be affected.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on larch
11
Epicormic growth can occur among dead branches of larch trees infected with Phytophthora ramorum.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Signs and symptoms on larch
12
Epicormic growth occurring among dead branches and extending down the stems of larch trees infected with Phytophthora ramorum.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Signs and symptoms on larch
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Profuse resin production associated with Phytophthora ramorum bark lesions. Here the resin is fresh and translucent.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Profuse resin production
Signs and symptoms on larch
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Profuse resin bleeds are associated with Phytophthora ramorum lesions on the stem and branches. The resin here has dried out to a white crust.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on larch
15
Resin exudation on a larch branch as a result of Phytophthora ramorum infection of the bark. Here the resin has dried to a white crust but is more subtle and less obvious.
Phot
ogra
ph: I
sobe
l Cam
eron
, For
estr
y Co
mm
issi
on
Signs and symptoms on larch
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Sometimes symptoms can be subtle such as this dead and discoloured side shoot associated with a Phytophthora ramorum lesion on a side branch of an infected larch tree.
Phytophthora ramorum lesion on a side branch of an infected larch causing the discoloration and death of side shoots. Resin production is associated with the lesion.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Dead side shoot
Dead side shoots
Fresh, translucent resin
Approximate position of lesion
Signs and symptoms on larch
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An infected larch side branch showing discoloration and death of side shoots. The outer bark has been removed to show the brown dead tissue of the lesion, the red/pink reaction tissue characteristic of a Phytophthora ramorum lesion and the healthy tissue beyond the lesion.
Foliage of larch becomes discoloured when stems or branches are girdled by Phytophthora ramorum lesions.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Healthy tissue
Approximate position of lesion
Yellow foliage
Dead brown lesion tissue
Pink reaction zone tissue
Signs and symptoms on larch
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Foliage of larch becomes discoloured when stems or branches are girdled by Phytophthora ramorum lesions.
Phot
ogra
ph: J
ohnn
y H
atha
way
, For
estr
y Co
mm
issi
on
Gingery-brown foliage
Signs and symptoms on larch
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Wilt and dieback of fresh growth. Distinct wilting/greying needles (often only retained towards tips of shoots).
Foliar symptoms of Phytophthora ramorum on larch associated with sporulation of the pathogen.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
amPh
otog
raph
: Mic
k Bi
ddle
, For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on larch
20
Grey/purple coloration of larch needles infected by Phytophthora ramorum and associated with sporulation of the pathogen. Note that frost damage can also cause needles to become discoloured and shoots to wilt and die.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
amPh
otog
raph
: Bar
naby
Wyl
der,
Fore
stry
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on larch
21
Phytophthora ramorum stem infection on a young Douglas fir leading to death of the top of the tree.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Douglas fir
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Phytophthora ramorum stem lesion on a young Douglas fir.
Phot
ogra
ph: A
lan
Ock
ende
n, F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on Douglas fir
23
Phytophthora ramorum infection on western hemlock foliage.
Dead shoot tips on western hemlock caused by Phytophthora ramorum.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
amPh
otog
raph
: Suz
anne
San
cisi
-Fre
y, F
ores
t Res
earc
h
Signs and symptoms on western hemlock
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Symptoms of larch canker (Lachnellula willkommii) on a side branch of infected larch.
Larch canker fruiting bodies (1–4 mm).
Phot
ogra
ph: D
avid
Ros
e, F
ores
try
Com
mis
sion
Phot
ogra
ph: B
arry
Lam
bsdo
wn,
For
estr
y Co
mm
issi
on
Look-alike signs and symptoms on larch
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Larch canker on stem showing sooty coloured resin exudation, fruiting bodies and stem deformation.
Phot
ogra
ph: B
arry
Lam
bsdo
wn,
For
estr
y Co
mm
issi
on
Look-alike signs and symptoms on larch
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The fungal pathogen Allantophomopsis pseudotsugae (previously known as Phacidium coniferarum) causes the death of twigs and small branches in larch trees (the photos here show symptoms on an Atlas cedar, Cedrus atlantica; however, the symptoms in larch look the same).
Phot
ogra
ph: R
ober
t Str
outs
, For
estr
y Co
mm
issi
onPh
otog
raph
: Rob
ert S
trou
ts, F
ores
try
Com
mis
sion
Look-alike signs and symptoms on larch
27
The fungal pathogen Allantophomopsis pseudotsugae causes the death of twigs and small branches in larch trees (the photo here shows symptoms on an Atlas cedar; however, the symptoms in larch look the same).
Phot
ogra
ph: R
ober
t Str
outs
, For
estr
y Co
mm
issi
on
Look-alike signs and symptoms on larch
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Signs and symptoms of larch woolly aphids (Adelges laricis). Needles are discoloured and shoots become defoliated. Note the white woolly secretions on needles.
Signs and symptoms of larch woolly aphids. Note the white woolly deposits on the needles.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Phot
ogra
ph: T
ony
And
erso
n, F
ores
try
Com
mis
sion
White woolly secretions
White woolly secretions
Look-alike signs and symptoms on larch
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Signs and symptoms of the larch case-bearer (Coleophora laricella). The needles become discoloured and die from the needle tip.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Phot
ogra
ph: F
ores
try
Com
mis
sion
Look-alike signs and symptoms on larch
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Larch trees that have been infested with the bark boring beetle Ips cembrae.
Phot
ogra
ph: M
yler
Cro
oke,
For
estr
y Co
mm
issi
on
Look-alike signs and symptoms on larch
31
Galleries of the bark beetle I. cembrae in European larch (L. decidua).
Phot
ogra
ph: T
helm
a W
ood,
For
estr
y Co
mm
issi
on
Look-alike signs and symptoms on larch
32
Signs and symptoms of a needle cast disease on larch caused by the fungal pathogen Meria laricis.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Look-alike signs and symptoms on larch
33
Signs and symptoms of a needle cast disease on larch caused by M. laricis. Note that the needles at the tip of the shoots look green and healthy while the needles along the remainder of the shoot have died.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Look-alike signs and symptoms on larch
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Typical shoot dieback and wilting rhododendron leaves caused by Phytophthora ramorum infection.
Early Phytophthora ramorum infection on Rhododendron ponticum. Note the wilting leaves.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
amPh
otog
raph
: Eve
rett
Han
sen,
Ore
gon
Stat
e U
nive
rsity
Wilting leaves
Signs and symptoms on Rhododendron ponticum
35
Wilting rhododendron leaves caused by Phytophthora ramorum infection.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Signs and symptoms on Rhododendron ponticum
36
Shoot dieback and wilting rhododendron leaves caused by Phytophthora ramorum infection. Note the bent over (shepherd's crook) appearance of the shoot, which occurs as the shoot dies back from the tip.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Rhododendron ponticum
37
Typical symptoms of a Phytophthora ramorum infection on a rhododendron leaf. The infection has entered the leaf both via the petiole and the leaf tip where water collects.
Typical symptoms of a Phytophthora ramorum infection on a rhododendron leaf. The infection has entered the leaf via the petiole and is progressing along the midrib.
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Signs and symptoms on Rhododendron ponticum
38
Leaf blotch on rhododendron can be caused by a number of different organisms such as Gloeosporium rhododendri and Septoria spp.
Phot
ogra
ph: R
HS,
Hor
ticul
tura
l Sci
ence
Phot
ogra
ph: S
uzan
ne S
anci
si-F
rey,
For
est R
esea
rch
Look-alike signs and symptoms on Rhododendron spp.
39
Woodland Vaccinium myrtillus infected with Phytophthora ramorum.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Vaccinium myrtillus
40
Woodland Vaccinium myrtillus infected with Phytophthora ramorum.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Vaccinium myrtillus
41
Woodland Vaccinium myrtillus infected with Phytophthora ramorum.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Vaccinium myrtillus
42
Infected woodland Vaccinium myrtillus showing symptoms that are typical of Phytophthora ramorum and Phytophthora kernoviae.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Vaccinium myrtillus
43
Infected woodland Vaccinium myrtillus showing symptoms that are typical of Phytophthora ramorum and Phytophthora kernoviae.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on Vaccinium myrtillus
44
Severe crown dieback on sweet chestnut trees caused by Phytophthora ramorum.
Phot
ogra
ph: M
ick
Bidd
le, F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on sweet chestnut
45
Prolific epicormic growth, with brown and wilting hanging foliage caused by Phytophthora ramorum.
Phot
ogra
ph: B
arna
by W
ylde
r, Fo
rest
ry C
omm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on sweet chestnut
46
Wilting, ‘water-soaked’ and discoloured foliage on epicormic shoots at the stem base of a Phytophthora ramorum infected sweet chestnut tree.
Phot
ogra
ph: M
ick
Bidd
le, F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on sweet chestnut
47
Sweet chestnut leaves infected with Phytophthora ramorum showing discoloured midribs.
Phot
ogra
ph: M
ick
Bidd
le, F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Phot
ogra
ph: F
ores
t Res
earc
h
Signs and symptoms on sweet chestnut
48
Clusters of dead leaves on a young sweet chestnut infected with a fungal pathogen (Cryphonectria parasitica) which causes chestnut blight.
Phot
ogra
ph: H
elen
Car
ter,
Fore
stry
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Look-alike signs and symptoms on sweet chestnut
49
Severe dieback in the crown of a sweet chestnut tree that is infected with Phytophthora cinnamomi.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Look-alike signs and symptoms on sweet chestnut
50
Stem bleeding caused by Phytophthora ramorum on beech.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on the bark of broadleaved trees
51
Stem bleeding caused by Phytophthora ramorum on beech. Note the bleeding can occur quite high on the stem.
Phot
ogra
ph: F
ores
try
Com
mis
sion
Eng
land
Tre
e H
ealth
team
Signs and symptoms on the bark of broadleaved trees
52
Birch tree infected with Phytophthora ramorum.
Phot
ogra
ph: B
en Jo
nes,
For
estr
y Co
mm
issi
on E
ngla
nd T
ree
Hea
lth te
am
Signs and symptoms on birch
53
Other pathogens can also cause bleeds on the bark of broadleaved trees such as bacteria (A), other Phytophthora spp. (B), honey fungus (C) and acute oak decline (D).
Phot
ogra
ph: F
ores
try
Com
mis
sion
Phot
ogra
ph: A
na P
érez
-Sie
rra,
For
est R
esea
rch
Phot
ogra
ph: A
na P
érez
-Sie
rra,
For
est R
esea
rch
Phot
ogra
ph: S
andr
a D
enm
an, F
ores
t Res
earc
h
Mycelium
C) Honey fungus bleed
Fruiting bodies
Bleed
D) Acute oak decline bleed
A) Bacterial wetwoodB) Phytophthora pseudosyringae bleed on beech
Look-alike signs and symptoms on the bark of broadleaved trees
This booklet forms part of a set that supports Observatree volunteers when out looking for priority pests and diseases. It supplements face-to-face training and is not intended as a full or detailed description. It will also be useful for others who have some knowledge of the particular pest or disease and understand how to look for these. Further information is available online from the websites listed below:
Observatree: www.observatree.org.uk
Forestry Commission: www.forestry.gov.uk
Forest Research: www.forestry.gov.uk/forestresearch
© Crown copyright 2017.
Published by Forest Research as part of the Observatree project.
Observatree aims to create a tree health early warning system using citizen science.
Funded by the EU’s LIFE programme, Observatree is a partnership project led by Forest Research, the research agency of the Forestry Commission. Project partners are Fera Science Ltd, Forestry Commission (GB and countries), the National Trust and the Woodland Trust. Supporting the project are the Animal & Plant Health Agency (APHA), the Department for Environment, Food & Rural Affairs (Defra) and Natural Resources Wales.
Acknowledgements:
Dr Suzanne Sancisi-Frey, Forest Research, for compiling this guide based on a review of current literature and with technical contributions from experts across the Observatree partnership.
All those who have given permission for images to be used within the guide.
The Communications Team, Forest Research, for the original design and creation of the guide.
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B-SS
F)/F
G61
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EC17
-16/
0034
Forest Research
